#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#define PI 3.14

int main()
{
    double r = 0.0;
    scanf("r=%lf", &r);
    double S = 0.0;
    S = PI * r * r;
    printf("S=%.2lf\n", S);

    return 0;
}